Theoretical investigation of DMPA-containing carbazole-based hole-transport materials for perovskite solar cells.

• DFT and TD-DFT modelling and extensive analysis of eight carbazole-based molecules as HTMs in perovskite solar cells. • Deep HOMO energy levels guarantee proper alignment with the perovskite material. • Acceptor core groups enhance charge transport properties. • Flatness is beneficial when the core consisted of two cycles, particularly for MP 2 P 2 M. • MP 2 P 2 M is distinguished by its superior charge transfer properties. This study mainly focuses on DFT and TD-DFT modelling and extensive analysis of eight carbazole-based molecules (MM, MPM, MP 2. 5 M, MP 2. 6 M, MP 3. 5 M, MPPM, MP 2 P 2 M, and MP 3 P 3 M) as Hole Transporting Materials in Perovskite Solar cells. These compounds have in common the arm N3,N3,N6,N6-tetrakis(4-methoxyphenyl)-9H-carbazole-3,6-diamine (M) characterized by its strong ability to carry holes, low cost, and good stability. The molecule MM presents two arms without acceptor core, while other compounds present two arms separated by different acceptor cores: phenyl, biphenyl, pyridine or bipyridine. All under-probe compounds were favored candidates for HTMs in perovskite solar cells due to their excellent HOMO delocalization, reduced hole reorganization energies, lower chemical reactivity, longer radiative lifetimes, and spontaneous solvation processes. Flatness proved beneficial when the core consisted of two cycles, particularly for MP 2 P 2 M. The results showed that the HOMO levels were primarily influenced by M fragments in most of the molecules, while the LUMO levels were distributed across both the carbazole units and the cores. All molecules exhibited a more stable LUMO compared to that of Spiro-OMETAD, with MP 2 P 2 M showing a notably stable level, resulting in a narrower gap. The study found that, except for MP 2 P 2 M, these materials did not interfere with the perovskite layer and effectively filled pores. The incorporation of acceptor core groups improved the conjugation backbone and electronic states, significantly enhancing charge transport properties, particularly in molecules with a double ring structure. Furthermore, adding a pyridine center greatly increased solubility, especially in MP 3 P 3 M, suggesting that acceptor core inclusion benefits the solubility of the investigated HTMs. The use of two rings core was shown to enhance light harvesting efficiency, boost photocurrent generation, and improve charge transfer performance, particularly in MP 2 P 2 M, which is distinguished by its superior flatness, solubility, and charge transfer properties. [ABSTRACT FROM AUTHOR]